Polyolefin yarns and method for manufacturing

ABSTRACT

The invention relates to a multifilament yarn having a tenacity of at least 30 cN/dtex, and comprising a plurality of spun ultrahigh molecular weight polyolefin filaments characterized in that the titer of any one of said spun filaments is at least 10 dtex.

This application is a continuation of copending U.S. application Ser.No. 14/653,149, filed Jun. 17, 2015, which is the national phaseapplication of International Application PCT/EP2013/077449, filed Dec.19, 2013, which designated the US and claims priority to EuropeanApplication No. 12198531.1, filed Dec. 20, 2012, the entire contents ofeach of which are hereby incorporated by reference.

The invention relates to a multifilament, ultrahigh molecular weightpolyethylene (UHMWPE) yarn having a high strength and a method formanufacturing thereof. The invention further relates to various productscontaining said yarn and in particular to the use of said yarn inapplications where cut resistance is desired, e.g. articles of apparelor rugged outerwear such as gloves, aprons, chaps, pants, boots, gators,shirts, jackets, coats, socks, shoes, undergarments, vests, waders,hats, gauntlets, and the like. The invention relates further to themonofilaments comprised in the described multifilament yarns.

Multifilament UHMWPE yarns are known for example from WO 2005/066401wherein a high-performance multifilament polyethylene yarn is disclosed,said yarn having very good mechanical and physical properties, e.g. hightenacity, modulus, abrasion and creep resistance. Also the yarns of WO2005/066401 preserve their good properties even when containing a largenumber of filaments, making them highly suitable for use in varioussemi-finished and end-use articles, examples thereof including ropes,cords, fishing nets, sports equipment, medical implants andballistic-resistant composites.

Among the above mentioned semi-finished and end-use articles, articlesof apparel or rugged outerwear used to protect the wearer against cutsform a special class. For example, the resistance to cut of gloves andother protective apparel, worn by individuals when e.g. handling andprocessing food, needs for a particular industry to be above a certainlevel to at least qualify for utilization thereof. A clear exampleconstitutes the meat packing industry where together with an increasedlevel of cut resistance, the protective articles need to provide thewearer with dexterity and tactile sensitivity also.

In consequence, it was observed that although the known multifilamentyarns of WO 2005/066401 show a collection of very good properties, theymay have a less optimum performance in some applications, in particularcut resistant applications. There is thus a need for further improvingthe known yarns to provide optimal cut resistance to products containingthereof. In particular there is a need for cut resistant fabrics whichare more versatile, i.e. fabrics that can be used in a broader range ofapplications where their cut resistance property is primarily needed.

The invention thus provides a multifilament yarn having a high tenacity,e.g. a tenacity of preferably at least 30 cN/dtex, and comprising aplurality of spun ultrahigh molecular weight polyethylene filamentscharacterized in that the titer of any one of said spun filaments is atleast 10 dtex.

It was observed that the yarn of the invention, hereinafter theinventive yarn, is highly damage tolerant and chemically resistant andprovides products containing thereof with improved cut resistance and/orcomfort. In particular it was observed that products comprising a fabriccontaining the inventive yarn behave very well during handling of oilyor wet articles, as they optimally resist against liquid accumulation onthe surface of the fabric.

By filament is herein understood an elongated body, the length dimensionof which is much greater than its transverse dimensions, e.g. diameteror the dimensions of width and thickness. Typically the transversedimensions of a filament are such that the ratio of the highestdimension of said cross-section to the lowest dimensions thereof is atmost 5, preferably at most 3. A filament, also called monofilament, isunderstood to be a monolithic elongated body obtained by a spinningprocess through a singular spin hole, in contrast to an aggregate ofmultiple filaments into a monofilament-like product. The term filamentincludes the embodiment of a fiber also and it may have regular orirregular cross-sections. The filaments typically have continuouslengths, however for certain utilizations they may be processed intoso-called staple fibers, i.e. filaments having discontinuous lengthscommonly obtained by cutting or stretch-breaking thereof. A yarn for thepurpose of the invention is an elongated body containing a plurality ofindividual filaments.

Preferably, the filaments of the inventive yarn have a titer of at least12 dtex, more preferably at least 14 dtex, even more preferably at least16 dtex, more preferably at least 18 dtex, most preferably at least 22dtex.

Preferably, the tenacity of the inventive yarn is at least 35 cN/dtex,more preferably at least 40 cN/dtex, most preferably at least 45cN/dtex. It was observed that such high tenacity yarns in addition tobeing highly suitable for use in cut resistant protective apparel, theyare also suitable for use in apparel designed to protect againstballistic impacts.

Preferably the inventive yarns have a titer of at least 50 dtex, morepreferably at least 100 dtex, most preferably at least 400 dtex.Preferably, for practical reasons, the inventive yarns have a titer ofat most 5000 dtex, more preferably at most 4000 dtex, most preferably atmost 3000 dtex. Preferably, the inventive yarn has a number of filamentsof at least 5, more preferably at least 24, most preferably at least 80.It was observed that the higher titer yarns of the invention may bemanufactured with processes which are conservative of capital and energyrequirements.

In a preferred embodiment, the inventive yarns have a tenacity of atleast 30 cN/dtex with filaments having a titer of at least 12 dtex, morepreferably at least 15 dtex, most preferably at least 20 dtex. It wasobserved that such yarns provide products containing thereof withincreased resistance against cutting.

In another aspect, the invention provides a multifilament yarn having ahigh tenacity, e.g. a tenacity of preferably at least 35 cN/dtex, andcomprising a plurality of spun ultrahigh molecular weight polyethylenefilaments characterized in that the titer of any one of said spunfilaments is at least 10 dtex, more preferably at least 12 dtex, mostpreferably at least 15 dtex. It was observed that such yarns provideproducts containing thereof with resistance against ballistic impacts.

In another embodiment, the inventive yarns contain filaments comprisinga hard filler. By hard filler is herein understood a filler having aMoh's hardness of at least 2.5, more preferably at least 4, mostpreferably at least 6. Good examples of suitable hard fillers includeglass fillers, mineral fillers or metal fillers. The fillers may haveany shape, e.g. a particulate shape, platelet, needle-like, fibre-like.In a preferred embodiment, the hard filler has a fiber-like shape withan average diameter of at most 20 microns, more preferably at most 15microns, most preferably at most 10 microns. Preferably the hardfiber-like filler has an average aspect ratio of at least 3, morepreferably at least 6, even more preferably at least 10, wherein theaspect ratio is the ratio between the length and the diameter of thehard fiber-like filler. The diameter and the aspect ratio of the hardfiber-like filler may easily be determined by using Scanning ElectronMicroscopy (SEM) pictures. For the diameter it is possible to make a SEMpicture of the filler as such, spread out over a surface and measuringthe diameter at 100 randomly selected positions and then calculating theaverage of the so obtained 100 values. For the aspect ratio it ispossible to make a SEM picture of one or more fiber-like fillers andmeasure the length of hard fibers. Preferably the SEM pictures are madewith backscattered electrons. Preferably the hard fiber-like fillers aremanufactured with a spinning technique. Advantage of such fillers isthat the diameter thereof has a substantially constant value which mayprovide the inventive yarn with excellent properties for use in cutresistant products.

The invention also relates to a multifilament yarn having a hightenacity, e.g. a tenacity of preferably at least 12 cN/dtex, morepreferably at least 15 cN/dtex, most preferably at least 17 cN/dtex, andcomprising a plurality of spun ultrahigh molecular weight polyethylenefilaments characterized in that the titer of any one of said spunfilaments is at least 10 dtex and wherein said filaments contain a hardfiller. The preferred embodiments of the hard filler are disclosedhereinabove. Preferably, the dtex of said filaments is at least 12, morepreferably at least 14, even more preferably at least 16, mostpreferably at least 18.

The inventive yarn may also contain filaments manufactured fromsynthetic materials other than UHMWPE; but also filaments manufacturedfrom natural materials and preferably having discontinuous lengths, i.e.natural staple fibers. Examples of natural staple fibers include but notlimited to fibers of cellulose, cotton, hemp, wool, silk, jute, sisal,cocos, linen and the like, with cotton being preferred. Examples ofnatural filaments include metal wire, glass filaments and the like. Itwas observed that yarns comprising cotton and the filaments of theinvention show very good comfort. Examples of filaments of syntheticpolymers include but not limited to those manufactured for example frompolyamides and polyaramides, e.g. poly(p-phenylene terephthalamide)(known as Kevlar®); poly(tetrafluoroethylene) (PTFE);poly{2,6-diimidazo-[4,5b-4′,5′e]pyridinylene-1,4(2,5-dihydroxy)phenylene}(known as M5); poly(p-phenylene-2,6-benzobisoxazole) (PBO) (known asZylon®); poly(hexamethyleneadipamide) (known as nylon 6,6),poly(4-aminobutyric acid) (known as nylon 6); polyesters, e.g.poly(ethylene terephthalate), poly(butylene terephthalate), and poly(1,4cyclohexylidene dimethylene terephthalate); polyvinyl alcohols.Preferred examples of synthetic filaments include polyester and/orpolyamide filaments having continuous and/or discontinuous lengths.

The invention also relates to a fabric comprising the inventive yarns.

The fabric of the invention, hereinafter the inventive fabric, may be ofany construction known in the art, e.g. woven, knitted, plaited, braidedor non-woven or combinations thereof. Woven fabrics may include plainweave, rib, matt weave and twill weave fabrics and the like. Knittedfabrics may be weft knitted, e.g. single- or double-jersey fabric orwarp knitted. An example of a non-woven fabric is a felt fabric. Furtherexamples of woven, knitted or non-woven fabrics as well as themanufacturing methods thereof are described in “Handbook of TechnicalTextiles”, ISBN 978-1-59124-651-0 at chapters 4, 5 and 6, the disclosurethereof being incorporated herein as reference. A description andexamples of braided fabrics are described in the same Handbook atChapter 11, more in particular in paragraph 11.4.1, the disclosurethereof being incorporated herein by reference.

Preferably the inventive fabric is a knitted fabric, more preferably awoven fabric, even more preferably the woven fabric is constructed witha small weight per unit length and overall cross-sectional diameter. Itwas observed that such a fabric shows a low weight per unit coveragesurface area and increased degree of flexibility and softness whilehaving an improved cut resistance when compared with known fabrics ofthe same construction.

The invention relates further to articles and in particular to articlesof apparel or rugged outerwear comprising the inventive fabric. Examplesof such articles include but are not limited to gloves, aprons, chaps,pants, boots, gators, shirts, jackets, coats, socks, shoes,undergarments, vests, waders, hats, gauntlets, and the like.

The invention also relates to the use of the inventive fabric inarticles of apparel or rugged outerwear and in particular in theexamples mentioned hereinabove.

In particular, the invention relates to gloves comprising the fabric ofthe invention. It was observed that the gloves of the invention may showgood comfort and also breathability. Preferably, the fabric contained bythe inventive gloves is a knitted fabric to enhance the fit and theflexibility of the glove.

It was observed that the inventive yarns have properties which also makethem an interesting material for use in ropes, cordages and the like,preferably ropes designed for heavy-duty operations as for examplemarine, industrial and offshore operations. Heavy duty operations mayinclude, but not restricted to, anchor handling, mooring of supportplatforms for offshore renewable energy generation, mooring of offshoreoil drilling rigs and production platforms and the like.

The inventive yarns are also very suitable for use as a reinforcingelement for reinforced products such as hoses, pipes, electrical andoptical cables, and in particular for reinforcing products used indeep-water environments. The invention therefore also relates to areinforced product containing reinforcing elements wherein thereinforcing elements contain the inventive yarns.

The invention also relates to medical devices comprising the inventiveyarns. In a preferred embodiment, the medical device is a cable or asuture, preferably used in implants. Other examples include mesh,endless loop products, bag-like or balloon-like products, but also otherwoven and/or knitted products. Good examples of cables include a traumafixation cable, a sternum closure cable, and a prophylactic or perprosthetic cable, long bone fracture fixation cable, small bone fracturefixation cable. Also tube-like products for e.g. ligament replacementare suitably manufactured from the inventive yarns. Such products madefrom the inventive yarns show an efficient ratio between their loadcarrying surface and their surface exposed to the human or animal body.It was further observed that the inventive yarns may be less prone toinfestation and may also allow for easier flush with sterilizing agents.

The invention further relates to composite articles containing theinventive yarns. Preferably, a composite article according to theinvention comprises a plurality of layers, wherein each of said layerscontains the inventive yarns, wherein said yarns are preferably arrangedin a parallel array, also known as unidirectional (UD) layers.

Multilayered composite articles proved very useful in ballisticapplications, e.g. body armor, helmets, hard and flexible shield panels,panels for vehicle armouring and the like. Therefore, the invention alsorelates to ballistic-resistant articles as the ones enumeratedhereinabove containing the inventive yarns.

It was also observed that the inventive yarns are also suitable for usein other applications like for example, fishing lines and fishing nets,ground nets, cargo nets and curtains, kite lines, dental floss, tennisracquet strings, canvas (e.g. tent canvas), nonwoven cloths and othertypes of fabrics, webbings, battery separators, capacitors, pressurevessels, hoses, (offshore) umbilical cables, electrical, optical fiber,and signal cables, automotive equipment, power transmission belts,building construction materials, cut and stab resistant and incisionresistant articles, protective gloves, composite sports equipment suchas skis, helmets, kayaks, canoes, bicycles and boat hulls and spars,speaker cones, high performance electrical insulation, radomes, sails,geotextiles and the like. Therefore, the invention also relates to theapplications enumerated above containing the yarns of the invention.

The invention also relates to sports equipment comprising the inventiveyarn, including a fishing line, a kite line and a yacht line. Theinvention also relates to a freight container having walls comprisingthe inventive yarn.

In another aspect of the invention, the multifilament yarn comprisesgel-spun UHMWPE monofilament having a high tenacity, e.g. a tenacity ofpreferably at least 30 cN/dtex, more preferably at least 35 cN/dtex, anda titer of at least 10 dtex, more preferably at least 12 dtex, mostpreferably at least 15 dtex. It was observed that a cutting device usingthe monofilament of the invention as the cutting element, show goodadvantages in particular in the food industry, e.g. for cutting boiledeggs or cheese products. In particular it was observed that thecleanability of the cutting device is optimum.

Therefore, the invention also relates to a gel-spun UHMWPE monofilamentand a cutting device comprising a cutting element, i.e. the element thatis used to part into smaller sections the product to be cut, saidcutting element comprising any one of the inventive yarns, preferablysaid cutting element comprising the inventive gel-spun monofilament.

In one embodiment of the invention, the gel-spun UHMWPE monofilament hasa strength per filament of at least 4.0 N, preferably of at least 4.5 N,more preferably of at least 5.0 N, even more preferably of at least 6.0N and most preferably of at least 7 N. It was observed that yarnscomprising the monofilaments of the invention as a strength element showadvantages in particular in sewing fabric, e.g. multicolor fabrics or asa fishing line. In particular it was observed that the monofilamentaccording to the invention provide seams that are hardly visible to thehuman eye by their virtue of fineness and transparency. Preferrably themonofilament according to this embodiment of the invention has atenacity of at least 20 cN/dtex, more preferably 25 cN/dtex and mostpreferably 30 cN/dtex. It was observed that monofilaments with highertenacity provide seams with further reduced visibility to the human eye.Therefor the invention also relates to a yarn comprising at least onemonofilament according to the invention, preferably the yarnsubstantially consists of the monofilament according to the invention.

The invention further relates to a method for manufacturing a yarncontaining a plurality of UHMWPE spun filaments, comprising in thefollowing order the steps of:

-   -   a. Providing a solution of UHMWPE in a suitable solvent,        preferably decaline;    -   b. Forcing said solution through a die containing a plurality of        apertures wherein the apertures issue said solution at a first        speed to form a plurality of filaments containing said solution;        each aperture having an exit with an exit diameter D_(ap)        ^(exit); each of said filaments having a diameter D_(fil) as        measured at the exit of said capillary;    -   c. Immersing said solution-containing filaments into a cooling        bath; preferably cooling water bath; and taking-up said immersed        filaments onto a take-up roll rotating at a second speed; and    -   d. Taking-out said filaments from the bath to form spun        filaments, at least partially extracting the solvent and drawing        said spun filaments in at least one drawing step before; during        and/or after said extraction;

-   wherein step b) is operated at a draw-down (DD_(op)), defined as the    ratio between the second speed and the first speed, of between 20%    and 90% of a resonance draw-down DD_(res);

-   wherein DD_(res) is the ratio between the second speed and the first    speed whereat D_(fil) fluctuates per minute with a percentage of at    least 25% between a maximum value D_(fil) ^(max) and a minimum value    D_(fil) ^(min); wherein the percentage is calculated with Formula 1

$\begin{matrix}{100 \times \frac{D_{fil}^{\max} - D_{fil}^{\min}}{D_{fil}^{avg}}} & {{Formula}\mspace{14mu} 1}\end{matrix}$

-   wherein D_(fil) ^(avg) is the average value of D_(fil) calculated    from a number of at least 10 measurements recorded during a minute.

It was observed that the inventive method is very stable, with a reducedamount of filament breakages and/or allowing for similar drawingpatterns for all filaments of the yarn. Also the inventive method allowsfor the production of yarns having an optimal combination of strengthand filament titer.

According to the inventive method, in step b) each aperture issues thesolution at a first speed, which is calculated as the ratio between thevolumetric flow of solution per aperture and the area

$\frac{\pi}{4}\left( D_{ap}^{exit} \right)^{2}$

of the aperture. The volumetric flow of solution per aperture can bereadily determined by dividing the volumetric flow of solution beforeentering the die by the number of the apertures. The volumetric flow ofsolution before entering the die can be readily set by using a spinningpump or an extruder. Preferably, all apertures are essentiallyidentical, in case apertures with different diameters are used, thevalues above are herein understood as average values.

At step c), the immersed filaments are taken-up onto a roll rotating ata second speed. By speed is herein understood the surface speed of saidroll. Said speed can be easily adjusted by using a driving motor todrive said roll.

According to the inventive method, the DD_(res) is determined fromanalyzing the fluctuations per minute of D_(fil). D_(fil) can be readilydetermined from calibrated photographs or by using a calibrated videocamera. D_(fil) is expressed in mm. In the present invention,

$100 \times \frac{D_{fil}^{\max} - D_{fil}^{\min}}{D_{fil}^{avg}}$

is at least 25%, more preferably at least 30%, even more preferably atleast 40%, most preferably at least 50%. It was observed that bychoosing a higher threshold for determining the DD_(res), the advantagesof the inventive method were more conspicuous. In particular for DD_(op)between 40% and 90% of DD_(res), more preferably between 50% and 90% ofDD_(res), most preferably between 60% and 90% of DD_(res), the inventivemethod operated at its optimum.

The draw-down (DD_(op)) at which step b) of the inventive methodoperates can be easily set, for example by first increasing thedraw-down to reach a draw-down resonance, as defined hereinabove, andthen decreasing the draw-down to the required value, e.g. at most 90% ofDD_(res). Preferably, DD_(op) is at most 85% of DD_(res), morepreferably at most 80%, most preferably at most 75%. It was observedthat the stability of the inventive method increases while reducing thedraw-down. DD_(op) is also at least 20% of DD_(res), preferably at least40%, most preferably at least 60%. Such values for DD_(op) are novel anddefy the common understanding in the art, since the current spinningprocesses for manufacturing UHMWPO filaments use values for DD_(op) inthe range of at most 5% of DD_(res). The common belief leading to usingvalues for DD_(op) so far away from DD_(res) are that the process ismore stable and by increasing the DD_(op) would only introduceinstabilities and filament breakages. However, the present inventorsdemonstrated to the contrary and achieved a high stability of theinventive method.

Preferably, the D_(ap) ^(exit) of each one of the apertures is at least1.5 mm, more preferably at least 2 mm, most preferably at least 3 mm.Preferably, said D_(ap) ^(exit) is at most 5 mm, more preferably at most4 mm, most preferably at most 3.5 mm. It was observed that even for suchlarge diameter apertures, the inventive method is very stable even whenusing an DD_(op) closer to DD_(res). Preferably, each aperture containsa capillary having a substantially constant diameter of at least 1.5 mm,more preferably at least 2 mm, most preferably at least 3 mm, whereinsaid diameter of the capillary is equal with D_(ap) ^(exit). Preferably,said diameter is at most 5 mm, more preferably at most 4 mm, mostpreferably at most 3.5 mm. It was observed that the inventive methodprovides very good results for capillaries having a diameter of between2 mm and 4 mm, most preferably between 2.5 mm and 3.5 mm, mostpreferably of about 3 mm. Preferably said capillary has an L/D_(ap)^(exit) ratio of at least 1.5, more preferably at least 2.0, mostpreferably of at least 2.5; with L being the length of the capillary.Preferably said L/D_(ap) ^(exit) ratio is at most 10, more preferably atmost 7.5, most preferably at most 5.

The apertures may also contain a so-called contraction zone, i.e. a zonewith a gradual decrease in diameter from a diameter D₀ to D_(ap)^(exit). The contraction zone preferably has an angle in the range8-75°. It is preferred that the apertures also contain the capillariesas defined immediately hereinabove, in this case, the contraction zonebeing preferably positioned upstream of the capillary.

At step b) of the inventive method the UHMWPE solution is forced throughthe apertures of a die at a first flow rate of preferably at least 1.4g/min/aperture; more preferably at least 2.0 g/min/aperture; even morepreferably at least 2.4 g/min/aperture. Preferably said first flow rateis between 2.0 g/min/aperture and 8.0 g/min/aperture; more preferablybetween 2.4 g/min/aperture and 7.7 g/min/aperture.

The herein described inventive process may allow the production of both,the inventive multifilament yarn as well as the inventive monofilaments.Here for the extruded filaments may be processed as described herein asa bundle of yarns or may be split at any stage of the process into oneor more monofilaments and an optional remainder of the multifilamentyarn composed of he remainder of monofilaments.

Preferably, the solution-containing filaments, hereinafter also referedto as fluid filaments, are issued at step b) of the inventive processinto an air-gap. Preferably, said fluid filaments are drawn in the airgap with a draw ratio of preferably at least 8, more preferably at least12, even more preferably at least 14, yet even more preferably at least16, most preferably at least 18. Preferably, the air gap has a length ofbetween 1 mm and 20 mm, more preferably between 2 mm and 15 mm, evenmore preferably between 2 mm and 10 mm, most preferably between 2 mm and5 mm. It was observed that such preferred air gap length may allow toreduce the draw rate in the air gap without substantially affecting yarntenacity.

In an alternative embodiment the fluid filaments are drawn in the airgap with a draw ration of between 3 and 12, preferably between 4 and 10and most preferably between 4 and 8. Such preferred draw ratio of thefilament in the air gap is especially suited for the production of yarnsand monofilaments with a high strength per filament measured on the yarnor a single filament as described in the experiments.

Although called air gap, said gap can be filled with any gas or gaseousmixture, e.g. air, nitrogen or other inert gases. By air gap is hereinunderstood the distance between the die and the cooling bath. Thecooling bath can be a liquid, e.g. water, containing bath at atemperature below the spinning temperature, e.g. about room temperature.In case the cooling bath is a liquid cooling bath, the minimum value ofthe air gap is preferably chosen to prevent any liquid surface wavesfrom touching the surface of the die.

Any of the known solvents suitable for spinning of UHMWPE can be used assolvent for making said solution, for example paraffin wax, paraffin oilor mineral oil, kerosenes, decalin, tetralin, or a mixture thereof. Itis found that the present process is especially advantageous forrelatively volatile solvents, preferably solvents having a boiling pointat atmospheric conditions of less than 275° C., more preferably lessthan 250 or 225° C. Suitable examples include decalin, tetralin, andseveral kerosene grades. The solution can be made using known methods;preferably, a twin-screw extruder is applied to make a homogeneoussolution from a slurry of UHMWPE in said solvent. The solution ispreferably fed to the die, also called spinplate, at constant flow ratewith metering pumps. The concentration of the solution is preferablybetween 3 and 25 mass %, with a lower concentration being preferred thehigher the molar mass of the polyolefin or polyethylene is. Preferably,the concentration is between 3 and 15 mass % for an UHMWPE with anintrinsic viscosity (IV) in the range 15-25 dl/g. The UHMWPE solution ispreferably formed at a temperature within at most 90° C. of the boilingpoint of the solvent, more preferably at most 70° C.

The UHMWPE preferably has an intrinsic viscosity (IV, as measured onsolution in decalin at 135° C.) of between about 8 dl/g and 40 dl/g,preferably between 10 dl/g and 30 dl/g, more preferably between 12 dl/gand 28 dl/g, most preferably between 15 dl/g and 25 dl/g. Intrinsicviscosity is a measure for molar mass (also called molecular weight)that can more easily be determined than actual molar mass parameterslike M_(n) and M_(w). There are several empirical relations between IVand M_(w), but such relation is dependent on molar mass distribution.Based on the equation M_(w)=5.37*10⁴ [IV]^(1.37) (see EP 0504954 A1) anIV of 4 or 8 dl/g would be equivalent to M_(w) of about 360 or 930kg/mol, respectively.

Preferably, the UHMWPE is a linear polyethylene with less than onebranch per 100 carbon atoms, and preferably less than one branch per 300carbon atoms; a branch or side chain or chain branch usually containingat least 10 carbon atoms. The linear polyethylene may further contain upto 5 mol % of one or more comonomers, such as alkenes like propylene,butene, pentene, 4-methylpentene or octene.

The UHMWPE that is used in the inventive process may further containsmall amounts, generally less than 5 mass %, preferably less than 3 mass% of customary additives, such as anti-oxidants, thermal stabilizers,colorants, flow promoters, etc. The UHMWPE can be a single polymergrade, but also a mixture of two or more different polymer grades, e.g.differing in IV or molar mass distribution, and/or type and number ofcomonomers or side groups.

In accordance with the invention, after taking out the filaments fromthe bath to obtain spun filament, said spun filaments is subjected to anextraction step wherein the solvent present therein is at least partlyremoved from the filaments. solvent removal can be performed by knownmethods, for example by evaporation if a relatively volatile solvent,e.g. decaline, is used; by using an extraction liquid; or by acombination of both methods.

The inventive method further comprises at least one drawing step whereinthe spun filaments are drawn in at least one stage preferably with adraw ratio of at least 4. Preferably, drawing is performed in at leasttwo stages, and preferably at different temperatures with an increasingprofile. The drawing preferably takes place between about 120 and about155° C. A 3-stage drawing is most preferred, with a total draw ratioDR_(total)=DR_(stage 1)*DR_(stage 2)*DR_(stage 3) of at least 10, morepreferably at least 20, most preferably at least 40.

In a preferred embodiment, the inventive method produces the inventiveyarn, wherein a die having apertures with a D_(ap) ^(exit) of at least 2mm, is used; a solution of at least 5 wt % UHMWPE of the total weight ofthe solution is used; a DD_(op) of at least 20% of DD_(res), is used;and a 3-stage drawing with a total draw ratio of at least 20 is used.Preferably, D_(ap) ^(exit) is at least 3 mm, more preferably between 2.5mm and 3.5 mm. Preferably, the UHMWPE solution has at least 6 wt %, morepreferably at least 8 wt %, most preferably at least 9 wt %. Preferablythe solvent is decaline. Preferably, DD_(op) is at least 40% ofDD_(res), most preferably at least 60%.

The invention will be further explained by the following examples andcomparative experiment, however first the methods used in determiningthe various parameters used hereinabove are presented.

-   -   dtex: yarn's or filament's titer was measured by weighing 100        meters of yarn or filament, respectively. The dtex of the yarn        or filament was calculated by dividing the weight (expressed in        milligrams) to 10;    -   IV: the Intrinsic Viscosity is determined according to method        ASTM D1601(2004) at 135° C. in decalin, the dissolution time        being 16 hours, with BHT (Butylated Hydroxy Toluene) as        anti-oxidant in an amount of 2 g/l solution, by extrapolating        the viscosity as measured at different concentrations to zero        concentration.    -   Tensile properties of fibers: tensile strength (or strength) and        tensile modulus (or modulus) are defined and determined on        multifilament yarns as specified in ASTM D885M, using a nominal        gauge length of the fibre of 500 mm, a crosshead speed of        50%/min and Instron 2714 clamps, of type “Fibre Grip D5618C”. On        the basis of the measured stress-strain curve the modulus is        determined as the gradient between 0.3 and 1% strain. For        calculation of the modulus and strength, the tensile forces        measured are divided by the titre, as determined by weighing 10        metres of fibre; values in GPa are calculated assuming a density        of 0.97 g/cm³. Strength per monofilament is determined by        multiplying the tenacity of the multifilament yarn in cN/dtex by        the dtex per filament of the yarn.

EXAMPLES 1-4

A slurry was prepared from 9 wt % UHMWPE having an IV of about 20 dl/gin decalin and fed to a co-rotating twin screw extruder to transform theslurry into a solution. The extruder and spinning head was heated at atemperature of 185° C. The solution was forced through a die having 24apertures with a rate of about 7.7 g/min (for examples 1 and 2) and 3.8g/min (for examples 3 and 4) per aperture.

The apertures contained a conical contraction zone with an angle of 15°upstream to a capillary having a D_(ap) ^(exit) of 3 mm and a length ofabout 8 mm.

The fluid filaments issued from the apertures entered an air gap andwere taken-up at such rate that a draw ratio as shown in Table 1 belowwas applied in the air gap. The DD_(op) at which the process is operatedis the same as the drawing ratio in the air gap and is in all casesabout 90% of the resonance draw down DD_(res).

Subsequently the fluid filaments entered a water bath where they werecooled and were taken up onto a take-up roll. Subsequently, they entereda first oven where they were drawn 8 times while the decalin evaporated.

From the first oven, the filaments entered a second oven where they weredrawn with various draw ratios as shown in Table 1 below together withyarn's properties.

TABLE 1 EX 1 EX 2 EX 3 EX 4 Draw ratio air gap 16 16 14 14 Length airgap (mm) 15 15 7 7 Draw ratio 2.2 3.0 2.0 2.5 dtex yarn (dtex) 424 315556 439 Tenacity yarn (cN/dtex) 29.4 29.8 25.2 28.3 Modulus yarn(cN/dtex) 1031 1241 897 1066 EAB yarn (%) 3.4 2.8 3.3 3.2 Filament titer(dtex) 18 13 23 18 Strength per filament (N) 5.3 3.9 5.8 5.1

EXAMPLES 5 AND 6

Example 1 was repeated with the difference that the yarn was furtherdrawn in a third step at about 149° C. Two draw ratios are applied asshown in Table 2 below.

TABLE 2 EXAMPLE 5 EXAMPLE 6 Third step's draw ratio 1.8 2.2 dtex yarn(dtex) 290 213 Tenacity yarn (cN/dtex) 34.3 42.6 Modulus yarn (cN/dtex)1390 1784 EAB yarn (%) 3.0 2.9 Filament titer (dtex) 12.1 8.9 Strengthper filament (N) 4.1 3.8

EXAMPLE 7

The material of Example 1 was knit into a fabric with an aerial densityof 260 g/m² (stitch density 10 gauge). For reference, a fabric was knitof the same construction, using a commercially available yarn of 440dTex containing 195 UHMWPE filaments, the yarn having a tenacity ofabout 31 cN/dtex and being sold by DSM Dyneema®, NL under the productname SK62.

Both fabrics were subjected to cut resistance testing according tostandard EN388, as well as standard ASTM 1790-05 (both in duplicate).Similarly, fabrics were subjected to the Martindale (EN388) abrasiontest, in which for each fabric type the numbers of cycles weredetermined where breakthrough observed. Results obtained are listed inthe Table 3 below:

TABLE 3 Test Reference Example 7 EN 388 - Cut index 2.5 6.0 EN 388 - Cutindex 3.7 6.1 ASTM F1790-05 Reference force 2.8 N 5.6 N ASTM F1790-05Reference force 2.7 N 5.6 N EN 388 Abrasion breakthrough cycles 1140cycles 3437 cycles

EXAMPLE 8

Example 1 was repeated; however, about 7% by weight of the totalsolution of a hard filler was added to the slurry prior to extrusion.The hard filler was mineral fibrils, i.e. a filler having fiber-likeshape, sold under the trade name CF10ELS by Lapinus, NL. The resultingyarn had a titer of 410 dTex, a tenacity of about 18 cN/Dtex and amodulus of about 850 cN/dTex.

The yarn was knit into a fabric with aerial density of 260 g/m² (Stitchdensity 10 gauge). For reference, a fabric was knit of the sameconstruction, using a commercially available yarn of 440 dTex containing130 UHMWPE filaments, the yarn having a tenacity of about 17 cN/dtex andcontaining the same type and amount of hard filler as the above.

Both fabrics were subjected to same cut resistance testing as detailedat example 7 above. The Martindale abrasion test was carried out 4 timefor each fabric. Results obtained are listed in the Table 4 below:

TABLE 4 Test Reference Example 8 EN 388 - Cut index 15.69 28.15 EN 388 -Cut index — 24.82 ASTM F1790-05 Reference force 11.1 N 21.2 N ASTMF1790-05 Reference force 11.1 N 20.9 N EN 388 Abrasion breakthrough 400cycles 1400 cycles EN 388 Abrasion breakthrough 459 cycles 1600 cyclesEN 388 Abrasion breakthrough 691 cycles 1800 cycles EN 388 Abrasionbreakthrough 1204 cycles 2200 cycles

EXAMPLES 9 AND 10

Example 1 was repeated, however, the fluid filaments were drawn about 19times in the air gap with a throughput per aperture of 5.7 g/min. In thefirst oven they were stretched 6 times. The yarn was drawn in a secondstep with various draw ratios as shown in Table 4 below, together withyarn's properties.

TABLE 5 EXAMPLE 9 EXAMPLE 10 Draw ratio 3.0 4.0 Dtex yarn (dtex) 347 263Tenacity yarn (cN/dtex) 30.9 34.7 Modulus yarn (cN/dtex) 1076 1269 EAByarn (%) 3.5 3.4 Filament titer (dtex) 14 11 Strength per filament (N)4.3 3.8

EXAMPLES 11 AND 14

Example 1 was repeated, however, the spinning head temperature wasreduced to 175° C., the fluid filaments were drawn about 5.7 times inthe air gap of a length of 4 mm and with a throughput per aperture of7.7 g/min. The filaments were drawn in the first and a second step withvarious draw ratios as shown in Table 6 below, together with yarn'sproperties. From the 24 filaments exiting the spin plate a singlefilament was individually processed resulting in examples 11 to 13 whilethe remaining 23 filaments were processed as a 23 filament yarn. Onlythe corresponding 23 filament yarn of example 13 is reported as example14 whereas the corresponding 23 filament yarns of examples 11 and 12 arenot reported.

TABLE 6 EX 11 EX 12 EX 13 EX 14 Filaments per yarn 1 1 1 23 Draw ratiofirst oven 12 12 14 14 Draw ratio second oven 2.1 2.5 2.1 2.1 dtex yarn(dtex) 35 30 30 672 Tenacity yarn (cN/dtex) 32.6 34.2 29.2 27.5 Modulusyarn (cN/dtex) 1099 1189 1009 1042 EAB yarn (%) 3.5 3.5 3.3 3 Filamenttiter (dtex) 35 30 30 29 Strength per filament (N) 11.4 10.2 8.8 8.0

1. A multifilament yarn having a tenacity of at least 12 cN/dtex, andcomprising a plurality of spun ultrahigh molecular weight polyethylenefilaments and a hard filler, characterized in that the titer of any oneof said spun filaments is at least 10 dtex.
 2. The yarn of claim 1,having a tenacity of at least 15 cN/dtex, preferably at least 17cN/dtex.
 3. The yarn of claim 1, having a filament titer of at least 12dtex, preferably at least 14 dtex, more preferably at least 16 dtex andmost preferably at least 18 dtex.
 4. The yarn of claim 1, having a titerof at least 50 dtex, preferably at least 100 dtex, most preferably atleast 400 dtex.
 5. The yarn of claim 1, wherein the filaments comprise ahard filler having a Moh's hardness of at least 2.5.
 6. The yarn ofclaim 1, wherein the hard filler include a glass filler, a mineralfiller or a metal filler.
 7. The yarn of claim 1, wherein the hardfiller has a fiber-like shape with an average diameter of at most 20microns, more preferably at most 15 microns, most preferably at most 10microns.
 8. The yarn of claim 1, further containing filamentsmanufactured from natural materials and preferably having discontinuouslengths said natural material being chosen from the group of materialsconsisting of cellulose, cotton, hemp, wool, silk, jute, sisal, cocoasand linen; with cotton being the preferred natural material.
 9. A fabriccomprising the yarn of claim
 1. 10. A glove comprising the fabricaccording to claim
 9. 11. A product chosen from the group of productsconsisting of fishing lines and fishing nets, ground nets, cargo netsand curtains, kite lines, dental floss, tennis racquet strings, canvas,nonwoven cloths and other types of fabrics, webbings, batteryseparators, capacitors, pressure vessels, hoses, (offshore) umbilicalcables, electrical, optical fiber, and signal cables, automotiveequipment, power transmission belts, building construction materials,cut and stab resistant and incision resistant articles, protectivegloves, composite sports equipment such as skis, helmets, kayaks,canoes, bicycles and boat hulls and spars, speaker cones, highperformance electrical insulation, radomes, sails and geotextiles, saidproduct comprising the yarn of claim
 1. 12. The spun UHMWPE monofilamentof the multifilament yarn of claim 1 wherein the monofilament is agel-spun monofilament with a tenacity of at least 30 cN/dtex and a titerof at least 10 dtex.
 13. A method for manufacturing the yarn of claim 1,comprising in the following order the steps of: a. Providing a solutionof ultrahigh molecular weight polyethylene and a hard filler, in asuitable solvent, preferably decaline; b. Forcing said solution througha die containing a plurality of apertures wherein the apertures issuesaid solution at a first speed to form a plurality of filamentscontaining said solution; each aperture having an exit with an exitdiameter D_(ap) ^(exit); each of said filaments having a diameterD_(fil) as measured at the exit of said capillary; c. Immersing saidsolution-containing-filaments into a cooling bath; preferably coolingwater bath; and taking-up said immersed filaments onto a take-up rollrotating at a second speed; and d. Taking-out said filaments from thebath to form spun filaments, at least partially extracting the solventand drawing said spun filaments in at least one drawing step before;during and/or after said extraction; wherein step b) is operated at adraw-down (DD_(op)), defined as the ratio between the second speed andthe first speed, of between 20% and 90% of a resonance draw-downDD_(res); wherein DD_(res) is the ratio between the second speed and thefirst speed whereat D_(fil) fluctuates per minute with a percentage ofat least 25%, between a maximum value D_(fil) ^(max) and a minimum valueD_(fil) ^(min); wherein said percentage is calculated with Formula 1$\begin{matrix}{100 \times \frac{D_{fil}^{\max} - D_{fil}^{\min}}{D_{fil}^{avg}}} & {{Formula}\mspace{14mu} 1}\end{matrix}$ wherein D_(fil) ^(avg) is the average value of D_(fil)calculated from a number of at least 10 measurements recorded during aminute.